The invention relates to a continuously operating developing machine of the type in which film to be developed travels through a plurality of processing stages, such as processing stages comprised of containers for baths of developing fluid, bleaching fluid, fixing fluid, washing water and stabilizing fluid.
In many developing machines of the general type in question, it has become customary to arrange a bleaching fluid bath downstream of the developing fluid bath. However, it has been found that the vapors arising from the bleaching fluid bath, which are the most chemically aggressive of the vapors arising from the processing fluid baths, can spread into other processing stages of the developing machine. Usually, the chemicals employed in the development of film in these machines are such that the vapors in question are ammonia vapors. These vapors do not pose too great a threat to the processing stage located downstream of the bleaching stage; however, these vapors pose a substantial threat to the developing stage located upstream of the bleaching stage. The entrance of ammonia vapors into the developing fluid bath can result in a purple-colored coating covering the film developed by the machine.
To avoid this difficulty, it is known to employ a venting apparatus operative for sucking ammonia vapors out of the space in the bleaching stage located above the bleaching fluid bath. This expedient is disadvantageous. In the first place, a separate source of energy must be employed to drive the venting apparatus. Additionally, metallic parts of the venting apparatus can become corroded in an extremely short time as a result of contact by the corrosive ammonia vapors, so that frequent replacement of such parts is necessary.